Cigarette filter rods have been processed in pairs in the so-called “two-up” filter rod configuration. According to this configuration, one solid filter plug is in the middle of a tube so that an empty space is created on either end of the filter tube. Each end is filled with a sequence of granular material, such as carbon and the like, and solid material, such as cellulose acetate fibers or fibers with flavorant. Upon completion a tobacco rod may be joined to each end of the filter tube, and the central solid filter may then be cut in half to form two cigarettes.
A separate assembly wheel may be arranged to fill each side of the tube. One end of the tube is filled on one assembly wheel by vertically depositing and/or inserting filter materials into the upwardly facing opening. The product is then transferred through a drum system or similar device to flip the tube along its longitudinal axis. The flipped tube, which has the filled end facing downward and the open end facing upward, is then placed on a second assembly wheel so that filter materials could be inserted or deposited into the open end.
U.S. application Ser. No. 11/268,291, which is incorporated herein by reference, teaches a method of filling the open ends of the filter tube, including filling one end of the tube, inverting the tube and filling the other end. The application describes a method which utilizes a rotating tube flute plate, a rotating bin of granular material, a plurality of vertically orientated fill tubes and second fill tubes, a rotating filter segment plate and second filter segment plate, and a plurality of rotating plungers, all of which collectively comprise an upper wheel assembly rotating about a central vertical axis. A substantially identical lower wheel assembly also rotates about the same central vertical axis. A first end of each filter tube is filled with solid and/or granular material on the upper wheel assembly. A conveyor system removes half-filled filter tubes from the upper wheel assembly, inverts the tubes and places them on the rotating tube flute plate of the lower wheel assembly. The other ends of the filter tubes are then filled with solid and/or granular material on the lower wheel assembly. It would be advantageous, however, if both sides of the fill tube could be filled using only one wheel assembly.
It is therefore an objective of the present invention to develop a method that uses a single wheel assembly, as described herein below, to assemble components into both ends of a hollow tube having a solid center.